menu thrown far right

Something gets too long on many posts of my Blog in phone view.
Example.
https://musictivity.org/2019/09/25/samanthafishkansas/
Here the width of Blog is much longer than width of screen.
Then my menu on top and my sharing buttons on the bottom are not entirely visible without scrolling right.

What exactly should I type into “additional CSS” field to make sure that width of Blog = width of screan, not more, not less, 100% ?

• This topic was modified 5 years, 2 months ago by moveyourears.

The page I need help with: [log in to see the link]